1. Field of the Invention
This invention relates generally to an adjustable fastener and, more particularly, to an adjustable fastener that can be used to secure the end of a brace strap.
2. Description of Related Art
Various types of buckles, clips, and other connectors that can be used in various orthotic and other types of devices such as to secure one end of a strap either to another portion of the same strap or to some other anchor point in the device are known to those of skill in the art. Some examples of previously disclosed buckles include those described in U.S. Pat. Nos. 3,112,496; 3,808,643; 3,827,107; 4,005,506; 4,310,110; 4,378,793; 5,201,100; 5,548,871; 5,502,843; 6,131,249; 6,163,941; 6,360,410; 6,631,537; 6,748,630; 6,760,958; and 6,766,532.
Not all types of fasteners are appropriate for any given particular application. In particular, there are special considerations for fasteners that are used to secure and tension straps on medical braces and other orthopedic devices. These fasteners should have an extremely low profile so that they do not interfere with the operation of the brace, hinder normal physiological movement of the body, or become accidentally opened if jarred. They also need to be able to allow the strap to be sufficiently tensioned and be of sufficient strength to withstand such tension force without failure. It is also beneficial if the fasteners are easy to operate so the patient can remove the device and easily returned to its original tension setting when the strap is refastened.
In the field of braces and orthopedic devices, two types of fasteners are prevalent. One of the most common type of fastener used are hook and loop fasteners (i.e. Velcro), often in combination with a D-ring. The D-ring is secured to an anchor point on the device, which may be one end of the strap itself or a brace shell or support. An end of the strap passes through the D-ring and doubles back on itself. The outer surface of the strap is composed of a material that forms the loop portion of the fastening system. At the end of the strap is a section of hooks that form the hook portion of the fastening system. The hook section can be used to secure the end of the strap to any point along the strap itself. By adjusting the location where the strap end is secured to itself, the length of the strap and hence the amount of tension that is applied by the strap can be controlled. If no D-ring is used, one portion of the fastener (e.g. the hook portion) can be located directly on an anchor point, such as a shell on a brace or the other end of the strap, and the other portion can be located on the end of the strap.
Hook and loop fastening systems are able to provide sufficient shear strength to prevent the strap from loosening or coming unfastened, while at the same time allowing the patient or physician to quickly and easily remove the strap and/or adjust the tension of the strap. It also can allow infinite variability in the amount of tension applied to the strap. While this type of fastener makes it easy for a patient to undo the straps to remove the brace when it is not needed, it can be difficult for the patient to refasten the strap with the exact amount of tension that was present when the strap was removed. In addition, hook and loop fasteners tend to wear out over time, especially when they are frequently opened and closed as would occur when a brace is removed daily for such activities as bathing, physical therapy, and/or sleeping. This may require the straps on a brace to be replaced every 3–6 months.
Another common category of fasteners in bracing and orthopedic devices is made up of various types of snap fasteners. While snap fasteners are more durable than the hook and loop fasteners, they are generally difficult to close when a significant amount of tension must be placed on the strap. The user often must place a higher amount of tension on the strap than the strap will provide once closed, while at the same time aligning the snap portions and often applying an additional force to snap the sections together. This is often difficult to achieve, especially for individuals who are weakened or have limited strength, and can result in the patient's skin being pinched between the portions of the snap. Many snap fasteners are also not adjustable. Adjustable fasteners that ratchet, such as are sometimes used in ski boots, have the ratcheting surface on the wide top surface of the strap and are too thick and bulky for use in braces and other orthotic devices. Therefore, there still remains a need for a fastener that is adjustable, easy to operate, and appropriate for use in braces and other orthotic devices.